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Pion photoproduction in the $\vec{\gamma }\vec{p}\to {\pi }^{0}p$ reaction has been measured in the FROzen Spin Target (FROST) experiment at the Thomas Jefferson National Accelerator Facility. In this experiment, circularly polarized photons with energies up to 3.082 GeV impinged on a transversely polarized frozen-spin target. Final-state protons were detected in the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer. The polarization observables $T$ and $F$ have been extracted for $W$ from 1445 to 2525 MeV, of which the energy range is much broader, and the precision is better than the existing measurements in higher $W$ ranges. The data generally agree with predictions of present partial-wave analyses but also show marked differences for higher $W$ ranges. By incorporating the present data into the databases, the Scattering Analysis Interactive Data (SAID) fits have been improved with relatively small ${\chi }^2$ and significant changes in the parameters of the $\mathrm{\Delta }\left(1910\right)1/2^{+}$ and $N\left(2190\right)7/2^{-}$ have been found with the JüBo model. 

Abstract A new type of radio frequency (RF) timing technique is presented. It is based on a helical deflector, which performs circular or elliptical sweeps of photo- or secondary electrons, accelerated to keV energies, by means of RF fields in the 500–1000 MHz range. By converting a time distribution of the electrons to a hit position distribution on a circle or ellipse, this device achieves extremely precise timing, similar to streak cameras. Detection of the scanned electrons, using a position sensitive detector based on microchannel plates and a delay line anode, resulted in a timing resolution of 10 ps, which can be potentially improved to 1 ps. RF-Timer-based single photon and heavy ion detectors have potential applications in different fields of science and industry, which include high energy nuclear physics and imaging technologies. This technique could play a crucial role in developing of sub 10 ps Time-of-Flight Positron Emission Tomography. 

Based on $334{\mathrm{pb}}^{-1}$ of photoproduction data collected with the GlueX detector at Jefferson Lab, we have measured for the first time the cross section of the exclusive reaction $\gamma +p\to \varphi \left(1020\right){\pi }^{+}{\pi }^{-}p$ by reconstructing the final state $K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}p$ produced with a photon beam of energies between 8.0 and 11.6 GeV. Based on the measured differential cross section, we have performed a search for the strangeoniumlike exotic candidate $Y\left(2175\right)$ , recently renamed to $\varphi \left(2170\right)$ . This state has been reported by different $e^{+}{e}^{-}$ annihilation experiments and it is addressed here for the first time in a photoproduction experiment. We do not find evidence for this state when using the resonance parameters quoted by the Particle Data Group and provide upper limits on the photoproduction cross section. Instead, we find a structure at a mass of $m\left(\varphi {\pi }^{+}{\pi }^{-}\right)=2.24\mathrm{GeV}/c^2$ with a statistical significance of about $5\sigma$ . The parameters of this structure differ from those quoted by the Particle Data Group for the $\varphi \left(2170\right)$ and are consistent with a previous observation in $e^{+}{e}^{-}$ annihilation. In addition, there is evidence for a second structure at $1.82\mathrm{GeV}/c^2$ . 

The experiment at Jefferson Lab has observed $p\overline{p}$ and, for the first time, $\mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ and $p\overline{\mathrm{\Lambda }}$ photoproduction from a proton target at photon energies up to 11.6 GeV. The angular distributions are forward peaked for all produced pairs, consistent with Regge-like $t$ -channel exchange. Asymmetric wide-angle antibaryon distributions show the presence of additional processes. In a phenomenological model, we find consistency with a double- $t$ -channel exchange process where antibaryons are created only at the middle vertex. The model matches all observed distributions with a small number of free parameters. In the hyperon channels, we observe a clear distinction between photoproduction of the $\mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ and $p\overline{\mathrm{\Lambda }}$ systems but general similarity to the $p\overline{p}$ system. We report both total cross sections and cross sections differential with respect to momentum transfer and the invariant masses of the created particle pairs. No narrow resonant structures were found in these reaction channels. The suppression of $s\overline{s}$ quark pairs relative to $d\overline{d}$ quark pairs is similar to what has been seen in other reactions. 

Inclusive electron scattering cross sections off a hydrogen target at a beam energy of 10.6 GeV have been measured with data collected from the CLAS12 spectrometer at Jefferson Laboratory. These first absolute cross sections from CLAS12 cover a wide kinematic area in invariant mass $W$ of the final state hadrons from the pion threshold up to 2.5 GeV for each bin in virtual photon four-momentum transfer squared $Q^2$ from 2.55 to $10.4{\mathrm{GeV}}^2$ owing to the large scattering angle acceptance of the CLAS12 detector. Comparison of the cross sections with the resonant contributions computed from the CLAS results on the nucleon resonance electroexcitation amplitudes has demonstrated a promising opportunity to extend the information on their $Q^2$ evolution up to 10 ${\mathrm{GeV}}^2$ . Together these results from CLAS and CLAS12 offer good prospects for probing the nucleon parton distributions at large fractional parton momenta $x$ for $W<2.5$ GeV, while covering the range of distances where the transition from the strongly coupled to the perturbative regimes is expected.